1. Field of the Invention
The present invention relates to a an adaptive connection admission control method using measurement and estimation of traffic in active service.
2. Description of the Prior Art
In a conventional Asynchronous Transfer Mode (ATM) network, congestion of the network may occur due to an unexpected traffic change of broad-band traffic, and thus a powerful and reliable traffic control mechanism for overcoming such problems is needed in an ATM system. A connection admission control system is used as a traffic control mechanism and determines whether a user's connection demand is accepted or not. A new connection is made only when a sufficient bandwidth is provided to such an extent that a quality of service (QoS) of the new connection can be guaranteed without lowering the QoS of existing services.
Conventional connection admission control methods are classified into two types. One is a method based upon a traffic parameter defined by a user, and the other is grounded on a measurement.
Generally speaking, as traffic parameters, representing a characteristic of a broad-band traffic, a peak cell rate and an average cell transmitting rate are used. The peak cell rate is readily defined as the reciprocal of the minimum interval between cells, but it is difficult to get an accurate average cell rate in advance because of its statistical characteristics.
Accordingly, the connection admission control method based upon a traffic parameter defined by a user is not accurate, and the efficiency of utilization of the bandwidth is conspicuously reduced if the traffic parameter is set inappropriately. Furthermore, in the case of the connection admission control method by a measurement, the traffic changes statistically and it is very difficult to set the measuring period of the measuring mechanism and the associated hardware, and therefore the measurement is hard to make accurately.